Should a superior defence technology become available, with a truck selected the user can click on a defense (with the Contruct mouse pointer), and the truck would rebuild it with the newer version. It would still however be at full cost, but it cuts out some navigation of the build menu, and manually demolishing old defences. The bonus of this is that a truck can be told to upgrade multiple obselete defences for automated upgrading of existing defences.
This would require each structure having a new entry in the CSV tables; upgradesTo. This would be a pointer to another defined structure. For example, R-Defense-MortarPit would have Mortar2Mk1-Pit as it's upgradesTo value. Some examples of technology obselence would be:
Cannon Hardpoints: WallTower02 -> WallTower03 -> WallTower04
Mortar Bunkers: R-Defense-MortarPit -> Mortar2Mk1-Pit -> Mortar3ROTARYMk1-Pit
Flamethrowers: Flame1Mk1 -> Flame2 -> Plasmite-flamer-bunker
Should a further techology down the tree become available, the defence upgrade will skip any obselete stages (ie, WallTower02 -> WallTower04).
One question I have is; should some defences be un-upgradable by this method? For example, should you be allowed to upgrade Mortar Bunkers to Howitzers Emplacements?
That's all I have; what do you think?
